DEVELOPMENT OF EUSTRONGYLIDES IGNOTUS (NEMATODA: DIOCTOPHMIDA) IN DOMESTIC DUCKS (ANAS PLATYRHYNCHOS DOMESTICA (L.))

Investigating the development of Eustrongylides ignotus in its definitive host would enable us to trace the complete life cycle of this nematode. Fourth-stage larvae isolated from naturally infected swamp eels (Monopterus albus) were used to infect domestic ducks (Anas platyrhynchos domestica [L.]). We observed that male and female worms exhibited different developmental patterns in host ducks. In males, the fourth molt occurred at day 1-2 post-infection (PI), after which they attained maturity on day 4 PI and died between day 7 and 9 PI. However, females underwent the fourth molt at day 2-4 PI, produced eggs from day 9 to 17 PI, and then degenerated and died. When compared 10 fourth-stage Female larvae, adult females demonstrated a considerable increase in total body size with a 151% increase in average body width and a 17% increase in average body length. However. the increase in size of the male larvae was not its significant as that in females. The average body width in adult males exhibited only a 45% increase over that in the larval stage.

Genetic differentiation in populations of the cestode Bothriocephalus acheilognathi (Cestoda, Pseudophyllidea) as revealed by eight microsatellite markers

The genetic structure of populations of the fish cestode, Bothriocephalus acheilognathi collected from Bailianhe Reservoir (BLH), Changshou (CSH) and Liangzi (LZH) Lakes was investigated by using 8 microsatellite loci. A total of 108 adult worms were genotyped at each of the 8 loci. For the 3 populations, the mean number of alleles per locus ranged from 2.38 to 5.5, and the mean expected heterozygosity ranged from 0.432 to 0.559. The average polymorphic information content (PIC) was from 0.384 to 0.492. The significant F-is values indicated non-random mating within LZH and BLH populations. On the other hand, when samples were further classified into subpopulations at the level of host fish species, no or little heterozygote deficiency was detected at most loci, showing that cross-fertilization, predominantly, but not exclusively, must have occurred within the subpopulations. Microsatellite markers also revealed an unexpected high level of genetic differentiation, as measured by R-st and N-m values or by deltau(2) genetic distance among subpopulations from different hosts. Factors influencing the population genetic structure and the parasite host specificity are discussed.

Growth of juvenile Chinese sturgeon Acipenser sinensis fed live and formulated diets

Triplicate groups of 3.8-g juvenile Chinese sturgeon Acipenser sinensis were reared for 8 weeks in indoor flow-through systems on one of four diets: a natural diet consisting solely of live tubificid worms, a semimoist practical diet, a dry practical diet, and a purified diet. The formulated diets were prepared in the laboratory and had protein contents of 47-50%. Except for the group fed the purified diet, fish showed high survival (94-96%) and growth (final weight, 41-45 g). Survival and specific growth rate did not differ significantly between groups fed the natural, semimoist, and dry practical diets, but were significantly (P < 0.05) lower in fish fed the purified diet. Proximate analysis showed that fish fed purified diet had lower protein and lipid levels but a higher moisture content than fish fed other diets. Our results demonstrated that growth and survival of cultured juvenile Chinese sturgeon fed practical diets were comparable with those fed live tubificid worms. However, Chinese sturgeon fed a purified diet showed inferior growth and survival.

Evidence of host blood feeding by the monogenean, Ancyrocephalus mogurndae (Monogenea : Ancyrocephalidae) from the gills of the mandarin fish, Siniperca chuatsi

By examining iron contents, it is demonstrated that the monogenean Ancyrocephalus mogurndae (Yamaguti, 1940) feeds on the blood of its host, the mandarin fish Siniperca chuatsi (Basilewsky). The iron content and then the quantity of blood necessary to produce this amount of iron are found different in young and fully-matured worms. Young worms contain higher levels of iron and estimated amount of blood. It is suggested that A. mogurndae may start to feed on host blood as attached on gills, and the amount of blood ingested by young worms may vary from 0.01 to 1.00 mu l before reproduction. The difference between young and fully-matured worms may be accounted for by the elimination of haematin and change of food composition in matured worms and may also be affected by reproduction. Experimental infections of the monogenean may provide supportive information for explaining the difference, and further studies should also examine the effect of immune components in host blood ol mucus on the intestines of the parasite.

Effect of ration and body size on the energy budget of juvenile white sturgeon

Growth and energy budget were measured for three sizes(2.4, 11.1 and 22.5 g) of juvenile white sturgeon Acipenser transmontanus held at 18.5 degrees C and fed tubificid worms at different levels ranging from starvation to ad libitum. For each size-class, specific growth rate increased linearly with increasing ration, and conversion efficiency was highest at the maximum ration. Growth rate decreased with increasing fish size at the maximum ration, but increased with size al each restricted ration. Conversion efficiency increased with increasing ration for each size-class and was usually highest at the maximum ration. Faecal production accounted for 3.2-5.2% of food energy. The proportion of food energy lost in nitrogenous excretion decreased with increasing ration. With increases in ration, the allocation of metabolizable energy to metabolism decreased, while that to growth increased. Fish size had no significant effect on the allocation of metabolizable energy to metabolism or growth. Al the maximum ration, on average 64.9% of metabolizable energy was spent on metabolism, and 35.1% on growth. (C) 1996 The Fisheries Society of the British Isles

个人信息管理的关键技术研究

随着互联网和移动通信等技术的飞速发展，以及普适计算模式代替传统的计算模式，使得每个人任何时候都处在信息的包围之中，并且面临的信息丰富多样。它们在人们的生活中的作用越来越大，但个人信息量日益增长，超越了个人对其管理控制的能力，使得个人处理信息面临越来越多的问题，如无法用有效的方式及时地记录随时遇到的信息、遗忘重要的提醒信息、个人花费大量的时间对信息进行组织和再查找操作等，这些严重影响了个人生活质量和工作效率，因此一个新的研究领域—个人信息管理(Personal Information Management, PIM)应运而生，并且目前已经成为研究的热点。 PIM研究个人在个人信息空间中获取、组织、检索和处理信息的活动过程。它是人们日常生活最基本的一部分，譬如个人经常要查找文件、管理Email、安排预约以及制定任务列表等。针对于PIM的信息非结构化、自然交互和个性化三大特点，以提高个人查找信息的效率以及快速开发PIM为目的，本文从个人信息的组织模式、PIM的实物界面隐喻、信息标签以及PIM的开发框架等关键技术上进行了研究。 本文首先介绍了PIM的研究发展现状，引出了当前对PIM研究的必要性和重要性。从个人日常对信息的需求过程分析，结合活动理论，研究了以活动为中心的个人信息的组织模式，提出了基于活动的信息项之间的相关度计算方法；接着讨论了适合笔式PIM的实物界面隐喻RSFDPF；通过分析个人信息特有的个人主观性属性，研究了个人主观的标签技术，以提高个人同信息交互的自然性以及查找信息的效率；最后针对笔式PIM的开发方法上，提出了基于模型驱动的快速开发适合不同人群和应用环境下的笔式PIM开发框架。 在本文所开展的对PIM的一些关键技术的研究中，主要的创新点包括： 1 基于活动理论，提出了以活动为中心的个人信息组织 当前的桌面计算机仍然是存放个人信息主要的地方，但是对个人信息的管理还是以应用程序-文档方式，单一的树形层次化结构管理个人信息，造成信息“孤岛”，影响个人执行复杂活动的效率，并且增加了个人记忆的负担。 通过分析用户执行多任务的交互场景，基于活动理论，将任务、任务相关的信息以及任务间的关系统一纳入活动研究的框架，从活动的静态结构、动态演变过程以及活动间的关系三方面对活动进行建模。 在个人完成复杂交互活动过程中，需要涉及多个信息项，由于信息项的在逻辑空间的分布性，造成用户组织、查找信息非常困难。个人信息项之间的相关性对于记忆和查找信息起着重要的线索作用，能够降低个人查找信息的认知努力。信息项之间的相关性不仅体现在信息的内容相似性上，而且隐含在个人对信息的交互活动过程当中，从这两个方面提出了定量计算信息项之间相关性的算法，根据个人活动模型，将参与活动的个人信息进行统一组织管理。 2 提出了笔式PIM的实物界面隐喻RSFDPF和基于主观方法的信息标签 当前层次结构化目录仍然是个人信息管理的主要方式，但是对于在笔交互环境中，已经严重影响了交互的自然性。 为了提高笔式PIM交互的自然性，通过分析个人在物理信息空间的办公室场景中处理个人信息的过程，将实物引入到界面中，建立了笔式PIM的实物界面隐喻：室-架-夹-桌面-堆-件(RSFDPF)，并对其进行了描述；另外，通过分析物理信息空间中个人对个人信息的主观属性，包括：个人对信息的看法、重要性等，提出将用户主观属性通过自然的笔式交互方式添加到个人信息之上，以提高个人查找和分类信息的效率。 3 提出了一种基于模型驱动的PIM开发框架 随着无所不在计算的日益发展，PIM被应用在越来越多的交互设备之上，其中笔式交互设备以其自然交互的特征和便携轻巧的物理特性迅速成为了新一代主流应用，但是笔式PIM需求的多样性、突出的个性化、应用设备和平台的差异性等特征，增加了开发笔式PIM的复杂度，如何缩短系统的开发周期，保证需求和实现的一致性以及系统的可扩充性和可移植性成了笔式个人信息管理系统开发的关键问题。 提出了一种基于模型驱动的开发笔式PIM的开发框架，建立了笔式PIM的开发模型和开发流程。 4 构建了面向研究工作者的笔式PIM原型 针对于研究者们进行的研究活动的大部分过程具有创造性和随意性以及所需要的信息组织具有非结构化和结构化混合等特点，基于模型驱动的PIM开发框架，构建了面向研究工作者的笔式PIM原型。

笔式用户界面敏捷开发工具及其应用

笔式用户界面软件是 Post-WIMP用户界面的一种主要形式，在普适计算环境下有着广泛的应用。笔式用户界面敏捷开发工具用可视化的方法支持用户界面的快速设计、减少手动开发的工作量，从而提高系统的开发效率。同时笔式用户界面软件敏捷开发工具还可以满足用户的个性化需求。具体来说，笔式用户界面敏捷开发工具就是通过场景和 UI 编辑来对用户需求建模并且通过 UI 来形象地展示。笔式用户界面软件敏捷开发工具采用基于场景设计的开发方法，设计结果形成 XML 格式的文档，通过解析这些 XML 文档自动生成基于 PBOP 平台的 C 代码。它可以将用户的业务逻辑层和系统应用层有效地分离，使得设计人员能够专注于业务逻辑和系统呈现，开发人员能够专注于具体应用逻辑的实现。 本文用到的主要理论与方法有：敏捷开发方法、模型驱动（MDA）开发方法、基于场景的设计方法、笔式用户界面PGIS范式、UI 形式化描述方法、代码生成模板。 本文通过对基于场景设计方法的研究分析，设计并实现了支持场景设计方法的场景设计工具。该工具将软件用户界面场景以图形形式展示给设计人员来发掘用户对软件用户界面的需求，同时又通过形式化的描述方法描述了场景的结构，使得代码生成工具能够根据场景形式化描述生成相应代码。通过定义笔式用户界面 PGIS 范式和它的形式化描述语言，使得 UI 编辑工具能够方便用户界面设计人员设计用户个性化的用户界面外观，并且形式化的描述语言能够方便代码生成工具生成笔式用户界面 UI 相关的代码结构。实践表明，笔式用户界面敏捷开发工具可以提高笔式用户界面软件的开发效率。 本文的主要工作有： 1、研究敏捷开发方法和 MDA 开发方法并提出通过实现 MDA 工具来实践敏捷开发方法。通过 MDA 工具来建立平台无关模型和平台相关模型之间的映射，帮助开发人员快速构建需求模型和搭建程序框架。 2、通过场景设计方法对用户的业务逻辑进行建模。通过场景树和状态迁移图的图形化表示帮助开发人员理解用户需求，通过场景的形式化描述方便代码生成工具抽取业务流程信息。 3、设计并实现了场景 UI 编辑器。通过场景 UI 编辑器可以直观地呈现应用系统的用户界面，并且通过修改 UI 属性可以满足用户对用户界面外观的个性化需求。引入了场景 UI 的形式化描述语言来帮助代码生成工具生成用户界面程序。 4、设计并实现了代码生成工具。通过解析场景形式化描述语言和场景 UI 形式化描述语言，抽取出有用信息，并通过定义好的程序模板将这些信息填入模板,从而提高了应用系统的开发效率。 5、以笔式 Email 系统作为一个应用实例串联使用笔式用户界面敏捷开发工具的流程。在此基础上介绍了几个实际的开发系统使用笔式用户界面敏捷开发工具设计的情况，以及对笔式用户界面敏捷开发工具未来的应用和改进做了展望。 关键词：笔式用户界面；用户界面设计工具；场景设计方法；UI 形式化描述与编辑；代码生成

网络测量技术研究与系统实现

近年来，计算机网络迅速发展，各种网络应用层出不穷，各种网络性能面临挑战。对网络流量进行识别和分类，对网络性能进行测量和分析，已成为计算机网络的一个新兴课题。网络测量能够了解网络的行为特征和性能特征等，是对网络进行规划建设和优化改造的基础。 本文以当前网络测量实际应用为背景，介绍了网络测量技术的发展、分类和商用产品，设计并实现了一种纯软件开发的、扩展性强、有实际应用价值的网络测量系统，并对实现过程中所涉及到的网络流量测量和网络性能测量关键技术作了详细描述。 本文工作主要有如下贡献： 1、提出了以纯软件方法开发网络测量系统的方案； 2、设计了网络测量系统的系统结构及各模块之间的接口； 3、设计并实现了网络流量测量子系统，能够监测和分析从数据链路层到应用层等不同协议层次的流量组成和变化趋势，以及主机对之间和服务器负载上的应用类型和流量，提供实时的和历史的流量统计分析功能，可协助分析和定位网络异常和网络瓶颈； 4、设计并实现了网络性能测量子系统，能够测量网络层端到端的跳数、丢包率、往返延迟、往返延迟抖动等参数，以及HTTP、TELNET、FTP和EMAIL等常见网络业务的应用层性能，协助用户分析影响网络性能的原因。

A close phylogenetic relationship between Sipuncula and Annelida evidenced from the complete mitochondrial genome sequence of Phascolosoma esculenta

Background: There are many advantages to the application of complete mitochondrial (mt) genomes in the accurate reconstruction of phylogenetic relationships in Metazoa. Although over one thousand metazoan genomes have been sequenced, the taxonomic sampling is highly biased, left with many phyla without a single representative of complete mitochondrial genome. Sipuncula (peanut worms or star worms) is a small taxon of worm-like marine organisms with an uncertain phylogenetic position. In this report, we present the mitochondrial genome sequence of Phascolosoma esculenta, the first complete mitochondrial genome of the phylum. Results: The mitochondrial genome of P. esculenta is 15,494 bp in length. The coding strand consists of 32.1% A, 21.5% C, 13.0% G, and 33.4% T bases (AT = 65.5%; AT skew = -0.019; GC skew = -0.248). It contains thirteen protein-coding genes (PCGs) with 3,709 codons in total, twenty-two transfer RNA genes, two ribosomal RNA genes and a non-coding AT-rich region (AT = 74.2%). All of the 37 identified genes are transcribed from the same DNA strand. Compared with the typical set of metazoan mt genomes, sipunculid lacks trnR but has an additional trnM. Maximum Likelihood and Bayesian analyses of the protein sequences show that Myzostomida, Sipuncula and Annelida (including echiurans and pogonophorans) form a monophyletic group, which supports a closer relationship between Sipuncula and Annelida than with Mollusca, Brachiopoda, and some other lophotrochozoan groups. Conclusion: This is the first report of a complete mitochondrial genome as a representative within the phylum Sipuncula. It shares many more similar features with the four known annelid and one echiuran mtDNAs. Firstly, sipunculans and annelids share quite similar gene order in the mitochondrial genome, with all 37 genes located on the same strand; secondly, phylogenetic analyses based on the concatenated protein sequences also strongly support the sipunculan + annelid clade (including echiurans and pogonophorans). Hence annelid "key-characters" including segmentation may be more labile than previously assumed.